Testing & Teaching
Indicator Lamp
In short
An indicator lamp is the simplest load: a part that uses electricity. Its terminals: L, N.
If this is your home: this page is written for heating engineers. Mains wiring and gas appliances are not DIY jobs; call a Gas Safe registered engineer. If you smell gas, leave the building and call the National Gas Emergency Service on 0800 111 999.
What it is
An INDICATOR LAMP is the simplest LOAD: a part that uses electricity. It lights when it has a live (L) on its L terminal and a neutral (N) on its N terminal. With either one missing, it is dark.
It has no earth core.
In the lessons it stands in for another part, to show where a live goes.
Terminals
| Terminal | What it is for |
|---|---|
| L (Live) | The live (L) in. |
| N (Neutral) | The neutral (N): the way back for the current, which completes the circuit. |
What the meter reads
A live and a neutral: it is lit.
A live alone: it is dark, but still live. That is 'live but dead': it looks dead, but its live can still give a shock.
Dead, across L and N the meter reads its FILAMENT, the thin wire that glows: about 180 ohms, cold, in this simulator.
Where it connects
Lessons that use it
- Cables
Foundation · Using the simulator
- A circuit: source, path, load, return
Foundation · Reading a circuit
- How a switch works: COM, NO and NC
Foundation · Reading a circuit
- The colours, and sleeving
Foundation · Electricity for heating controls
- Permanent and switched lives
Foundation · Electricity for heating controls
- The dual channel programmer
Foundation · The parts
- The single channel programmer
Foundation · The parts
- A maker's terminal map
Intermediate · Reading branded units
Also in testing & teaching
Practise it in the simulator.
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